Electronic shift and shift lock device



Nov. 8, 1966 w K. ROBINSON ELECTRONIC SHIFT AND SHIFT LOCK DEVICE P iledMay 7, 1965 TO ENCODER INVENTOR WILL/AM K. ROB/NSO/V BY 5 A ATTORNEYUnited States PatentOfifice 3,283,873 Patented Nov. 8, 1966 3,283,873ELECTRONIC SHIFT AND SHIFT LOCK DEVICE William K. Robinson, St. Paul,Minn., assignor to Sperry Rand Corporation, New York, N.Y., acorporation of Delaware Filed May 7, 1965, Ser. No. 453,990 3 Claims.(Cl. 197-71) This invention relates to the electronic typewriterkeyooard and in particular to an electronic circuit for the shift andshift lock keys which are used to cause upper case characters to beprinted.

The conventional mechanical typewriter keyboard has oeen generallyreplaced by electromechanical keyboards. Further, in many systems suchas alphanumeric display systems, telegraph, teletype and computersystems, electromechanical keyboards are used. These electromechanicalkeyboards do not type out characters as does the conventional typewriterbut instead cause an encoder to set up an electrical code that is thensent to the printer which types the character. Thus, when a key isdepressed by an operator, the electrical code is produced for that keyand is sent to a printer which types the character represented by thatkey.

. The prior art has made little or no provision for an electronic shiftand shift lock key. For example Patent Number 3,129,418 which disclosesan electronic key board makes no provisions whatsoever for an electronicshift or shift lock key. In Patent Number 3,104,388 provisions are madefor obtaining capital and lower case letters but these provisionsinclude a light source, apertured discs, a plurality of photo cells andso forth. In other systems, mechanical linkage is used to hold the shiftlock key down.

- The circuit of the present invention eliminates the need formechanical linkage as well as apertured discs, light sources and soforth and provides a simple electrical circuit which will produce a coderepresenting an upper case character whenever a shift key is depressedand, when the shift lock key is momentarily depressed, will produce acode representing upper case characters until such time as the shift keyis momentarily depressed. This operation is similar to that performed onthe standard typewriter keyboard.

The present invention includes a relay having three coils which cause asingle-pole double-throw switch to assume either one of its twopositions to produce a coded output signal representing either an uppercase or a lower case character. A first one of the coils is normallyenergized thus holding the single-pole double-throw switch in a firstone of its positions to represent a lower case character. Whenevereither of the right or left shift keys is depressed, a second one of thecoils is energized which cause the switch to move from its firstposition to its second position thus providing an output signalrepresenting an upper case character. The second coil remains energizedonly so long as either the right or left shift keys is depressed.Whenever one of the shift keys is depressed; not only is the second coilenergized but the first coil is deenergized. This enables thesingle-pole switch to move from its first position to its secondposition. When the shift key is released, the voltage is removed fromthe second coil and re-applied to the first coil which causes the singlepole switch to return to its original position representing a lower casecharacter.

Whenever the shift lock key is depressed, a second relay is energizedwhich closes a first contact that locks the second relay in itsenergized position. The second relay also opens a second contact whichremoves the potential from the first coil in the first relay. Further itapplies a potential to the third coil in the first relay thus causingthe single pole switch to move from its first position representing alower case character to its second position which represents the uppercase character. Whenever either of the two shift keys are momentarilydepressed, the energizing circuit to the second relay is momentarilybroken thus causing the holding circuit of the second relay to be lostand, when the shift key is released, the normally closed contact on thesecond relay again applies a potential to the first coil of the firstrelay thus causing the switch to be returned to its first position whichrepresents a lower case character.

Thus it is an object of the present invention to provide an electronicshift circuit for an electronic keyboard which produces encoded signalsrepresenting lower case characters.

It is another object of the present invention to provide an electronicshift lock circuit for an electronic typewriter keyboard in which, whenthe shift locked key is depressed, an encoded signal representing uppercase characters is produced.

These and other more detailed and specific objects will be disclosed inthe course of the following specification, reference .being had to theaccompanying drawings, in which FIG. 1 is a representative view of atypewriter key attached to a microswitch having three electricalcontacts and,

FIG. 2 discloses the electrical circuitry forming the novel shift andshift lock circuit which produces encoded signals representing uppercase and lower case characters.

FIG. 1 shows a standard typewriter key 2 mechanically attached tomicroswitch 4 which includes switching circuit 1 having electricalcontacts or terminals 6, 8, and 10 attached thereto. Battery 5 iscoupled between ground and contact 6. Contact 6 of microswitch 4 isnormally coupled to contact 10 and no coupling normally exists betweencontact 6 and contact 8. However, when key 2 is depressed, the circuitconnecting contact 6 and contact 10 opens and the open circuit betweencontact 6 and 8 closes.

As will be seen in FIG. 2, signal generator 12 is a relay, K1, andincludes single-pole double-throw switch 14 and contacts 16 and 18 withwhich switch 14 is associated. Signal generator 12 also includes threecoils 20, 22, and 24. When coil 20 is energized, switch 14 is forced tocontact 16. When either of coils 22 or 24 is energized, switch 14 isforced to contact 18.

The right switching circuit 4a, the left switching circuit 4b and theshift lock switching circuit 40 as shown in FIG. 2 represent the base ofmicroswitch 4 shown in FIG. 1 with its associated contacts 6, 8, and 10.Remembering that when the key is not depressed, contact 6 iselectrically connected to contact 10, it will be seen that when avoltage or potential is applied to contract 6 of the right switchingcircuit 4a, this potential is coupled to contact 10 of circuit 4a towhich is coupled conductor 26. Conductor 26 couples the voltage fromcontact 10 of the right switching circuit 4a to contact 6 of the leftswitching circuit 4b. Again, the contact 6 of the left switching circuit4b is electrically connected to contact 10 of circuit 4b. Thus thevoltage at contact 6 of the left switching circuit 41) is transferred tocontact 10 of circuit 4b and there via conductor 28 is, coupled tocontact 6 of the shift lock switching circuit 40. The voltage at contact6 of the shift lock switching circuit 40 is coupled via line 30 to thejunction of normally open contact 32 and normally closed contact 34 ofrelay 36, K2. Since contact 34 is normally closed, the potential at thejunction of contacts 32 and 34 is connected to coil 20 of relay 12, K1.Since the other end of coil 20 is coupled to a ground potential throughresistor 40, it will be understood that coil 20 is normally energizedand, thus, forces switch 14 against contact 16. Therefore, the closedcircuit between conductors 42 and 44, which are connected to theencoder, is a code which represents a lower case character.

When it is desired to cause a capital or upper case character to beprinted, either the right shift key or the left shift key may bedepressed. Conductor 48 interconnects contact 8 of both the rightswitching circuit 4a and the left switching circuit 4b. When either theright shift key or the left shift key is depressed, the potential oncontact 6 of the associated switching circuit 4a or 4b is coupled toconductor 48 and the potential is removed from contact 10 of theswitching circuit associated with the shift key which is depressed.Conductor 50 which is coupled to coil 22 in signal generator 12 throughdiode 52, is also connected to contact 8 of switching circuit 4b. Thus,when either the right shift key or the left shift key is depressed, thepotential which is then coupled to line 48 is also present on line 50which passes through diode 52 to energize coil 22 of relay 12. Also itwill be seen that when either of the shift keys is depressed, thepotential is removed from contact 10 of switching circuit 4b thus removing the potential from lines 28 and 30 which are coupled throughnormally closed contact 34 of relay 36 to coil of relay 12. Thus, coil20 is de-energized while coil 22 is energized. The result is to causeswitch 14 to be forced from contact 16 to contact 18. This causes aclosed circuit or code to appear between conductors 42 and 46, which arecoupled to the encoder, and which represents an upper case or capitalcharacter. The encoder forms no part of the present invention and willnot be discussed. It will also be seen that when the depressed shift keyis released, the potential is removed from lines 48 and 50 whichde-energizes coil 22 in relay 12 while the potential is re-establishedon conductors 28 and which re-energizes coil 20. Thus, switch 14 isforced from contact 18 to contact 16 which once more presents a closedcircuit on lines 42 and 44 which represent to the encoder a lower casecharacter.

When a series of capital or upper case characters are to be printed, theshift lock key is depressed momentarily. This causes the potential oncontact 6 of switching circuit 40 to be connected to pin 8 of switchingcircuit 40 to which conductor 54 is connected. The potential on contact8 of the circuit 4c energizes coil of relay 36, K2, through conductor54. When relay 36 is energized, it closes normally open contact 32 andopens normally closed contact 34. When normally open contact 32 isclosed, the potential on contact 6 of circuit is coupled via conductor30 and normally open contact 32 (which is now closed) to relay 36 whichforms a holding circuit for relay 36 and keeps it energized. After thedepressed shift lock key is released, the potential from contact 6 ofswitching circuit 40 is coupled to contact 8 via conductor 30, contact32 and conductor 54. Conductor 56 which is also coupled to contact 8 ofswitching circuit 40 is connected to one end of coil 24 in signalgenerator 12 through diode 58. Since the other end of coil 24 isconnected to a ground source through resistor 40, coil 24 is energized.It will also be seen that since relay 36, K2, is energized and normallyclosed, contact 34 is now opened, the voltage will be removed from coil20 thus causing it to be de-energized. Since coil 24 is energized andcoil 20 is de-energized, switch 14 is forced from contact 16 to contact18 thus causing a closed circuit on lines 42 and 46 to be connected tothe encoder to represent a capital or upper case character.

Output leads 42 and 46 will then continue to produce signals to theencoder representative of upper case or capital characters until suchtime as either the right shift key or the left shift key is momentarilydepressed. When either of these keys is momentarily depressed, thevoltage is removed from normally closed contact 10 of switching circuit4b which removes voltage from conductor 28. It is the voltage on line 28that is coupled through line 30 and contact 32 which holds relay 36energized. Therefore, when the voltage at contact 10 of switchingcircuit 4b is removed the holding circuit for relay 36 is broken andrelay 36 becomes de-energized. When this happens, contact 34 of relay 36is again closed thus coupling coil 20 to contact 6 of switching circuit40. When the momentarily depressed shift key is then released, thevoltage is coupled once again to pin 10 of the switching circuit 40 andis coupled from there via lines 28 and 30 and contact 34 to coil 20which energizes thus causing switch 14 to be forced from contact 18 backto contact 16. Once again then the closed circuit on output conductors42 and 44 to the encoder represents lower case characters.

Thus, the keyboard electronic shift and shift lock circuit comprisesfirst and second shift keys and a shift lock key each movable betweenfirst and second positions, a signal generator 12 for producing a firstelectrical code on conductors 42, 44 representing lower case charactersand a second electrical code on conductors 42, 46 representing uppercase characters, said signal generator 12 comprising a first relayhaving a conducting arm 14 movably associated with a pair of electricalcontacts 16, 18, and a plurality of operating coils 20, 22 and 24 formoving said arm from one of said contacts to the other, an electricalswitching circuit 4a, 4b coupled to said first and second shift keysrespectively for producing a first signal on terminal 10 thereof onlywhen both of said keys are in said first position and a second signal oncontact 8 thereof only when either of said keys is in said secondposition, each of said switching circuits 4a, 4b comprising asingle-pole double-throw switch operatively associated with each of saidshift keys and having an input terminal 6 and two output terminals 8, 10whereby a first one 10 of said output terminals is coupled to said inputterminal 6 when said associated key is in said first position and thesecond one 8 of said output terminals is coupled to said input terminal6 when said associated key is in said second position, means 26 couplingsaid first output terminal 10 of said switching circuit 4a associatedwith said first key to the input terminal 6 of said switching circuit 4bassociated with said second key to produce said first signal on saidfirst output terminal 10 of said switching circuit 4b associated withsaid second key, means 48 coupling said second output terminals 8 ofsaid switching circuits 4a, 4!) together to produce said second signalon conductor 50 and a voltage source 5 connected to the input terminal 6of said switching circuit 4a associated with said first key forselectively energizing the coils 20, 22, 24 of said relay 12 dependingupon the position of the shift keys, a second relay 36 having anenergizing coil 35, a first pair of normally open contacts 32 whichclose to form a relay holding circuit when said second relay 36 isenergized and a second pair of normally closed contacts 34 which openwhen said relay 36 is energized, means 28, 30, 38 coupling said firstsignal to coil 20 of said signal generator 12 through said normallyclosed pair of con tacts 34 for causing said signal generator 12 toproduce said first code on conductors 42, 44, means 50 coupling saidsecond signal to coil 22 of said signal generator 12 for causing saidsignal generator to produce said second code on conductors 42, 46, anormally open switch in switching circuit 40 operatively associated withsaid shift lock key, said switch being closed when said shift lock keyis in said second position, means 28, 54 coupling said first signal tosaid energizing coil 35 through said switch in switching circuit 40whereby said first signal energizes relay 36 whenever said shift lockkey is in said second position, means 30, 54 coupling said first signalto said energizing coil 35 of relay 36 through said normally opencontacts 32 to form a locking circuit when-- ever relay 36 is energized,said locking circuit holding said relay 36 energized until either ofsaid shift keys is momentarily placed in said second position tointerrupt said first signal on line 28, and means 56 coupling 3,283,8736 the energizing coil 35 of relay 36 to coil 24 of said sigwherein saidrelay is a first relay and said signal gennal generator for causing saidsignal generator to produce erator comprises: said second code onconductors 42, 46 as long as said (a) a second relay having relay 36 isenergized. (1) a conducting arm movably associated with a Thus it willbe seen that a very simple yet effective 5 pair of electrical contacts,and electronic shift and shift lock circuit is disclosed by the (2) aplurality of operating coils for moving said present invention whichavoids the use of open blade arm from one of said contacts to the other,switches which are actuated by levers attached to keys, (b) means forcoupling said first signal to one of said which need frequent adjustmentand which allow paper, coils for causing said arm to engage a first oneof dust and dirt to collect on the contacts. said contacts to producesaid first code,

It is understood that suitable modifications may be (0) means forcoupling said second signal to a second made in the structure asdisclosed provided such modione of said coils for causing said arm toengage the fications come within the spirit and scope of the appendedsecond one of said contacts to produce said second claims. Having now,therefore, fully illustrated and decode, and scribed my invention, whatI claim to be new and desire ((1) means for coupling said energizingcoil of said to protect by Letters Patent is: first relay to a third oneof said coils for causing 1. A keyboard electronic shift and shift lockcircuit said arm to engage the second one of said contacts comprising:to produce said second code as long as said first relay (a) first andsecond shift keys and a shift lock key each movable between first andsecond positions, (b) a signal generator for producing a firstelectrical code representing lower case characters and a secondelectrical code representing upper case characters,

(c) an electrical switching circuit coupled to said first and secondshift keys for producing a first signal only when both of said keys arein said first position and a second signal only when either of said keysis in said second position,

(d) a relay having an energizing coil, a first pair of normally opencontacts which close to form a relay holding circuit when said relay isenergized and a second pair of normally closed contacts which open whensaid relay is energized,

(e) means coupling said first signal to said signal generator throughsaid normally closed pair of contacts for causing said signal generatorto produce said first code,

(f) means coupling said second signal to said signal generator forcausing said signal generator to produce said second code,

(g) a normally open electrical switch operatively associated with saidshift lock key, said switch being closed when said shift lock key is insaid second position,

(h) means coupling said first signal to said relay energizing coilthrough said switch whereby said first is energized. 3. A keyboard shiftand shift lock circuit as in claim 2 wherein said electrical switchingcircuit comprises:

(a) a single-pole double-throw switch operatively associated with eachof said shift keys and having an input and two output terminals wherebya first one of said output terminals is coupled to said input terminalwhen said associated key is in said first position and the second one ofsaid output terminals is coupled to said input terminal when saidassociated key is in said second position,

(b) means coupling said first output terminal of said switch associatedwith said first key to the input terminal of said switch associated withsaid second key to produce said first signal on said first outputterminal of said switch associated with said second y,

(c) means coupling said second output terminals of saiccll switchestogether to produce said second signal, an

(d) a voltage source connected to the input terminal of said switchassociated'with said first shift key for selectively energizing thecoils of said first and second relays depending upon the position of theshift keys and the shift lock keys.

References Cited by the Examiner UNITED STATES PATENTS 1,976,352 10/1934Maul 234-96 signal energizes sa1d relay whenever said shift lock2,739,649 3/1956 Hamel et 1 34 9 X y 18 111 sa1d s d P P 2,902,0929/1959 Hildebrandt 234-23 (1) means coupling said first signal to sa1denergizing 2,928 467 3/1960 Lindberg 234 9 X coil of said relay throughsaid normally open con- 3 017,463 1/1962 Dinsmore-ezzl 34Q 365 X tactsto form a locking circuit whenever said relay 3,021,993 2/1962 Brewer u"34 23 X is energized, said locking circuit holding said relay 3 104 3889/1963 Balenger 340 345 energized until either of said shift keys ismomen- 3,129,413 4 /1964 De La 1 34 345 tarily placed in said secondposition to interrupt said 1 1 5 11/1964 11 u fi slgfial, Q 3,194,4937/1965 Brewer 234-124 X (1) means coupling the energ1zing coil of sa1drelay to 3,212,702 10 1 5 J h t 234 124 said signal generator forcausing said signal gen erator to produce said second code as long assaid relay is energized.

2. A keyboard shift and shift lock circuit as in claim 1 ROBERT E.PULFREY, Primary Examiner.

E. S. BURR, Assistant Examiner.

1. A KEYBOARD ELECTRONIC SHIFT AND SHIFT LOCK CIRCUIT COMPRISING: (A)FIRST AND SECOND SHIFT KEYS AND A SHIFT LOCK KEY EACH MOVABLE BETWEENFIRST AND SECOND POSITIONS, (B) A SIGNAL GENERATOR FOR PRODUCING A FIRSTELECTRICAL CODE REPRESENETING LOWER CASE CHARACTERS AND A SECONEELECTRICAL CODE REPRESENTING UPPER CASE CHARACTERS, (C) AN ELECTRICALSWITCHING CIRCUIT COUPLED TO SAID FIRST AND SECOND SHIFT KEYS FORPRODUCING A FIRST SIGNAL ONLY WHEN BOTH OF SAID KEYS ARE IN SAID FIRSTPOSITION AND A SECOND SIGNAL ONLY WHEN EITHER OF SAID KEYS IS IN SAIDSECOND POSITION, (D) A RELAY HAVING AN ENERGIZING COIL, A FIRST PAIR OFNORMALLY OPEN CONTACTS WHICH CLOSE TO FORM A RELAY HOLDING CIRCUIT WHENSAID RELAY IS ENERGIZED AND A SECOND PAIR OF NORMALLY CLOSED CONTACTSWHICH OPEN WHEN SAID RELAY IS ENERGIZED, (E) MEANS COUPLING SAID FIRSTSIGNAL TO SAID SIGNAL GENERATOR THROUGH SAID NORMALLY CLOSED PAIR OFCONTACTS FOR CAUSING SAID SIGNAL GENERATOR TO PRODUCE SAID FIRST CODE,(F) MEANS COUPLING SAID SECOND SIGNAL TO SAID SIGNAL GENERATOR FORCAUSING SAID SIGNAL GENERATOR TO PRODUCE SAID SECOND CODE, (G) ANORMALLY OPEN ELECTRICAL SWITCH OPERATIVELY ASSOCIATED WITH SAID SHIFTLOCK KEY, SAID SWITCH BEING CLOSED WHEN SAID SHIFT LOCK KEY IS IN SAIDSECOND POSITION, (H) MEANS COUPLING SAID FIRST SIGNAL TO SAID RELAYENERGIZING COIL THROUGH SAID SWITCH WHEREBY SAID FIRST SIGNAL ENERGIZESSAID RELAY WHENEVER SAID SHIFT LOCK KEY IS IN SAID SECOND POSITION, (I)MEANS COUPLING SAID FIRST SIGNAL TO SAID ENERGIZING COIL OF SAID RELAYTHROUGH SAID NORMALLY OPEN CONTACTS TO FORM A LOCKING CIRCUIT WHENEVERSAID RELAY IS ENERGIZED, SAID LOCKING CIRCUIT HOLDING SAID RELAYENERGIZED UNTIL EITHER OF SAID SHIFT KEYS IN MOMENTARILY PLACED IN SAIDSECOND POSITION TO INTERRUPT SAID FIRST SIGNAL, AND (J) MEANS COUPLINGTHE ENERGIZATING COIL OF SAID RELAY TO SAID SIGNAL GENERATOR FOR CAUSINGSAID SIGNAL GENERATOR TO PRODUCE SAID SECOND CODE AS LONG AS SAID RELAYIS ENERGIZED.